I like the new(ish) addition to http://www.w3.org/DesignIssues/LinkedData.html on 5-star data. Unfortunately it looks like TimBL typed it with his eyes shut :-)
Since it's a much read and much referenced document, I'd like to offer the following version with typos corrected. Perhaps someone with permission to edit this page might want to copy and paste it in.
Cheers
Bill
Is your data 5 Star?
(Added 2010). This year, in order to encourage people - especially government data owners - along the road to good linked data, I have developed this star rating system.
★ Available on the web (whatever format), but with an open licence
★★ Available as machine-readable structured data (e.g. Excel instead of image scan of a table)
★★★ As (2) plus non-proprietary format (e.g. CSV instead of Excel)
★★★★ All the above, plus: use open standards from W3C (RDF and SPARQL) to identify things, so that people can point at your stuff
★★★★★ All the above, plus: link your data to other people’s data to provide context
How well does your data do? You can buy 5 star data mugs, T-shirts and bumper stickers from the W3C shop at Cafepress: use them to get your colleagues and fellow conference-goers thinking 5 star linked data. (Profits also help W3C :-).
Now in 2010, people have been pressing me, for government data, to add a new requirement, and that is there should be metadata about the data itself, and that that metadata should be available from a major catalog. Any open dataset (or even datasets which are not but should be open) can be registered at ckan.net. Government datasets from the UK and US should be registered at data.gov.uk or data.gov respectively. Other countries I expect to develop their own registries. Yes, there should be metadata about your dataset. That may be the subject of a new note in this series.